1. Field of the Invention
The present invention relates to pixel display circuits and, more particularly, to a method for driving these circuits to provide integrated data and gate multiplexing.
2. Description of the Related Art
Due to poor charging ability in amorphous silicon thin film transistors (a-Si TFTs) resulting from inherently low TFT transconductance, all commercially available a-Si TFT liquid crystal displays (LCD) include an array of pixel elements connected with row and column metal lines. The row and column drivers require higher transconductance devices. The row and column drivers typically include crystalline silicon technology and are separately fabricated and attached to the a-Si TFT LCDs. Over the years, there have been attempts at integrating some level of multiplexing between the attached crystalline silicon drivers and the pixel array. See for example, U.S. Pat. No. 5,175,446 to R. Stewart. In this way, the number of crystalline drivers needed could be reduced. These prior art designs follow a circuit approach that is commonly used in crystalline silicon circuit designs. Even simple 2:1 level multiplexing schemes at the edge of a pixel array have not been implemented for a-Si TFT LCD circuits. Although not realized for direct view a-Si TFT LCDs, multiplexer circuits have been implemented with some success in smaller displays for example, in light valves and in poly-silicon technology. Poly-silicon TFTs make it possible to realize a higher transconductance TFT. However, implementing poly-silicon technology on larger and/or high resolution TFT LCDs becomes unacceptable due to higher RC load and/or higher bandwidth rates of the rows and columns.
Therefore, a need exists for a control circuit for providing integrated data and gate multiplexing for active matrix LCDs without impacting acceptable display limits. A further need exists for a method of driving these displays which compensates for feedthrough voltage, an effective value and gate waveform delay.